The present invention relates to cut lumber processing and handling devices that will allow greater manufacturing efficiency and lower costs while increasing quality of the resulting products. More specifically, the present invention relates to a scanner which will operate in cooperation with a printer which will print results derived from the scanning operation on each lumber place for subsequent sorting and handling in a lumber mill.
In present-day in lumber mills, the practice has become common of increasing throughput speeds in order to reduce costs and to take advantage of increased processing speeds made possible by the use of operational sensors and computers. However, when new equipment is installed in a production line, it is desirable that the production speed of the original equipment not be compromised. It sometimes happens in established mills that new equipment can be operated efficiently at higher speeds than the already installed equipment so that some type of accommodation is required to minimize any reduction in the through put speed and capacity of the mill operation.
A difficulty in enhancing mill production capacity is the wide variety as well as the number of defects in the lumber that are encountered. Some of these defects cannot be accurately detected by automatic sensors particularly those operating at the increased conveying speeds presently in use. As a consequence, human inspection is still required for some grades of lumber. Such human inspections can take place where the lumber path is required to turn through as much as 90xc2x0 such as when the lumber is passed from a planing device to a sorting device in a mill operation. With the increasing scarcity of good grade of lumber, the types and variety of the defects in the lumber are likely to increase so that the necessity of effective scanning, electronically and by visual inspection, before sorting is correspondingly increased to assure that the final product is marketable.
The present invention provides an arrangement for a lumber mill and a method of operation that will enable a mill operator to maintain the production capacity while taking advantage of increased grading accuracy speeds afforded by presently available defect scanning devices. In addition, a mounting arrangement for a symbol printer is provided to improve the flexibility of the printing operation relative to conveying apparatus conventionally used in lumber mills.
More specifically, in presently operating mills and in other environments, it has been the practice to employ slowdown conveyors to transition lumber pieces from one processing device to a subsequent processing device and were the movement of the lumber piece changes from lineal to lateral motion. In cooperation with at least one of the slowdown conveyors where a sequential series are employed, at a printing station, a printing boom is installed which includes a lateral translation device to move a symbol printer over the path of travel of the conveyor to allow the printer to mark pieces of lumber that are passing beneath the printer station. The printer output is preferably a symbol that will enable a downstream positioned inspector to confirm the classification of the lumber piece set by the scanning device.
With this arrangement control of the production speed can be maintained without diminishing the production rate of the mill.